RESUMEN
The development of many quantum optical technologies depends on the availability of single quantum emitters with near-perfect coherence. Systematic improvement is limited by a lack of understanding of the microscopic energy flow at the single-emitter level and ultrafast timescales. Here we utilize a combination of fluorescence correlation spectroscopy and ultrafast spectroscopy to capture the sample-averaged dynamics of defects with single-particle sensitivity. We employ this approach to study heterogeneous emitters in two-dimensional hexagonal boron nitride. From milliseconds to nanoseconds, the translational, shelving, rotational and antibunching features are disentangled in time, which quantifies the normalized two-photon emission quantum yield. Leveraging the femtosecond resolution of this technique, we visualize electron-phonon coupling and discover the acceleration of polaronic formation on multi-electron excitation. Corroborated with theory, this translates to the photon fidelity characterization of cascaded emission efficiency and decoherence time. Our work provides a framework for ultrafast spectroscopy in heterogeneous emitters, opening new avenues of extreme-scale characterization for quantum applications.
RESUMEN
To understand the effects of additives on the performance of a Ni-Co-P alloy electroplated coating, this study, based on a single-factor experiment, utilized a Box-Behnken experimental design to optimize an additive that can enhance the electrodeposited Ni-Co-P alloy coating's properties, including hardness, glossiness, and corrosion resistance. The study used tools such as a gloss meter, a Vickers hardness tester, and an electrochemical workstation to analyze the impact of different additives on the coating's hardness and gloss. The optimal additive combination was determined. The results from the Box-Behnken experiment showed that when the concentrations of sodium dodecyl sulfate, thiourea, and sodium allyl sulfonate reached 0.10, 0.15, and 0.22 g/L, respectively, the resulting coating hardness was 475.4 HV0.5, and the gloss level was 463.4 GU. Compared to the coatings without additives, the hardness increased by 90.34 HV0.5, and the glossiness rose by 101.2 GU. The coating's corrosion resistance also improved. This enhancement is attributed to the compounded additive, which significantly improved the surface morphology of the coating, making it smoother and more compact. The morphology and composition of the coatings with additives were analyzed through scanning electron microscopy and energy dispersive X-ray spectroscopy, and the composition of the coating contains 71.01 at % Ni, 20.65 at % Co, and 8.34 at % P. At the same time, the optimized coating exhibits a metallic luster similar to stainless steel, meeting industrial requirements.
RESUMEN
A partially neutralized polyacrylic acid (Pn-PAA) is used for coating sub-micron-sized α-alumina on a conventional microporous polyolefin separator, fabricating a ceramic-coated separator (CCS). Pn-PAA acts as a dispersant and binder by adsorbing itself on alpha(α)-alumina surfaces under acidic condition through the columbic interaction, providing a repulsive force to disperse fine alumina in aqueous suspension, and binds alumina strongly on plasma-treated separator through hydrogen bonding. This CCS shows favorable wettability in carbonate-based liquid electrolyte and ionic conduction due to the high hydrophilicity of Pn-PAA and alumina. With that, this study found that Pn-PAA-made-CCS yields a substantial adhesion strength of ~106â N/m with enhanced cycle stability, a specific capacity of 145.0â mAh/g after 200â cycles at 1â C at room temperature in half cells (LFP/Li metal).
RESUMEN
We investigate multiple photon-assisted Landau-Zener (LZ) transitions in a hybrid circuit quantum electrodynamics device in which each of two interacting transmission-line resonators is coupled to a qubit, and the qubits are driven by periodic driving fields and also coupled to a common phonon mode. The quantum state of the entire composite system is modeled using the multi-D2Ansatz in combination with the time-dependent Dirac-Frenkel variational principle. Applying a sinusoidal driving field to one of the qubits, this device is an ideal platform to study the photon-assisted LZ transitions by comparing the dynamics of the two qubits. A series of interfering photon-assisted LZ transitions takes place if the photon frequency is much smaller than the driving amplitude. Once the two energy scales are comparable, independent LZ transitions arise and a transition pathway is revealed using an energy diagram. It is found that both adiabatic and nonadiabatic transitions are involved in the dynamics. Used to model environmental effects on the LZ transitions, the common phonon mode coupled to the qubits allows for more available states to facilitate the LZ transitions. An analytical formula is obtained to estimate the short time phonon population and produces results in reasonable agreement with numerical calculations. Equipped with the knowledge of the photon-assisted LZ transitions in the system, we can precisely manipulate the qubit state and successfully generate the qubit dynamics with a square-wave pattern by applying driving fields to both qubits, opening up new venues to manipulate the states of qubits and photons in quantum information devices and quantum computers.
